i have no power in my car for anything lights,dome lights, not even to start the blazer...what could it be

 

check the connections at the battery

also get the battery tested
have you checked the fuses yet?

 

yes i got a new battery put it on and nothing same..you see what had happen was me and my dad where changing th altternater but forgot to unplug the pos and the grnd cables. something sparked by thealternater and now nothing wants to work.

 

Sounds like you fried a fusible link. The battery cables themselves have fusible links in them. With the battery connected, test for power at the large terminal on the starter.

 

we checked the fusible link right bu the starter and it came out good, any ideas of what else it could be